In-situ crosslinking of polysiloxane electrolyte within Al$_2$O$_3$@SiNWs for quasi-solid-state micro-supercapacitors

Developing flexible solid-state micro-supercapacitors with large potential window is crucial for many technologies. The present study focuses on the synthesis and elaboration of quasi-solid-state (QSS) electrolytes with an electrochemical stability greater than 3.0 V based on functionalized polysiloxane. Their electrochemical behavior was studied with silicon nanowires electrodes. The polysiloxane was functionalized with both ammonium and cross-linkable functions. The nanostructured electrodes were impregnated with a mixture of ionic liquid and functionalized polysiloxane. The crosslinking of the polymer electrolyte was then performed by thermal curing directly within the nanostructured electrodes. The quasi-solid system exhibits very high stability upon galvanostatic cycling i.e. during 100 000 cycles with a cell potential of 3.0 V only a capacitance loss of 2.10$^{−5}$% per cycle was registered. The performance of this QSS with safe electrolyte is remarkable.